FIREARM. 634 FIRE-CLAY. niting the charge, which projects a mass of metal or other material through the force of the ex- panding gases developed by the burning of a charge of gunpowder. Some sort of firearm in which stones were employed as projectiles was in use bj' the Chinese in the eighth century. By the year 1200 firearms were in use among the Mongols, and there are reports of their use by Genghiz Khan in 1258. The Mohammedan pow- ers, then in the height of. their development as regards science and art, seem to have been familiar with the use of firearms in the twelfth century, and had developed practicable small arms in the thirteenth. Early in the fourteenth century cannon came into general use in Europe, and by the end of that century cannon and small arms had become common. See Artillery ; Ballistics; (,im:ky; Gunpowder; Ordnance; Small Arms, etc. FIRE-ARMOR. See Fire Protection. FIREBACK. A pheasant of the Malayan ge- nus Euplocomus, in which all the species have red plumage on the back. See Pheasant. FIRE-BALL. A projectile designed, when discharged from gun or mortar, to set tire to an enemy's defensive works, or for giving illumina- tion during operations against him. Fire-balls were the successors to the fire-arrow of ancient warfare, and have in turn been superseded by the rocket and other modern inventions. FIRE-BELLIED FROG. See Feuerkrote. FIRE-BILL. A paper giving in detail the stations and duties of officers and men of a ->'l of war upon the alarm of fire. When the new of a ship are at their stations as defined in the fire-bill the gathering is known as fire- quarters. All precautions arc taken against fire, and pumps, hose, and extinguishers are prepared for use. FIRE-BLIGHT, or PEAR-BLIGHT. One of the most destructive diseases of pears, apples, and other pomaceous fruits. While not as regu- lar in its attack as some other plant diseases, no other is more destructive when it docs appear. Fire-blight is a contagious bacterial disease due to Micrococcus amylovorus, which gains entrance through the soft tissues of new growth such as twigs and young fruits, through wounds made by insects or otherwise, bul especially through the nectaries and stigmatic surfaces of the blos- som, from which point of infection the bacteria rapidly spread, killing the t issues as they progress. The [eaves are sometimes attacked, bul usually they die as a result of tin' destruction of the twigs, and they remain dried and attached to the branches, forming one of the most striking fea- tures of the disease. The part attacked is the cambia] layer of the twigs, down which the dis- pa ' in the branches, and finally to the 1 1 uiik, lis rate of progress is not very rapid. when it lias run its course, the line of demarkation between sound and dead wood i- een. Upon bea ring 1 1 ee - i he in rl place >>f attack i- Usually in the blossoms, the ".ernis being spread from Bower to flower ami from tree ree bj bees ami ot her insects. The di sea e ■ aized b] < In in oi bl is turn- black. I 'rom i he e i he disease spreads. It i er in infect inns 1 1ml li:u e oc curved late in the summer, The infected bark is . and in the spring gum exudes from the diseased area. This is especially attractive to bees, which carry the germs from the gum to the flowers. Rapid growth of the trees, which may be.caused by severe pruning or by too much nil ro genous food in the soil, favors the spread of the disease. Anything that will check the growth of the trees, such as withholding cultivation and nitrogenous fertilizers, should be adopted. The must satisfactory treatment is to cut out and burn all blighted limbs while the trees are dor- mant. All parts suspected of infestation should be carefully examined and severely pruned back six inches or a foot below the line of separation between sound and diseased wood. The best time to do this is in the autumn, when the contrast between the diseased and sound branches is most striking. A careful inspection of the trees should be made several times during the summer, and all new infections should be cut out and burned. If all pear, apple, quince, crab, hawthorn, and al- lied plants be looked after in this way, the serious spread of the disease may, to a great degree, he prevented. For a full account of this disease, consult Waite. in United States Department of Agricul- ture Yearbook for 1895 (Washington, 1896). FIRE-BOAT. See Fire-Engixe. FIRE-BOTE. See Estover. FIRE-BRICK. See Brick. FIRE-CLAY. A variety of clay capable of withstanding a high degree of heat. This is because it contains such a low percentage of fluxing impurities such as iron, lime, magnesia. and alkalies. A good fire-clay should resist a temperature of 2900° F., and some will resist 3500°; but, unfortunately, many clays are called fire-clays which are not really refractory. Fire- clays are often plastic, but in the United States especially there exists a non-plastic variety known as 'flint clay.' Fire-clay is found in many geological formations, and in the Carboniferous rocks is often associated with coal. In the United States it is found in large quantities in the Carboniferous rocks of Pennsylvania. Ohio, Mis- souri, and Kentucky, and in the Cretaceous of New Jersey and other States, especially Colo- rado. Large quantities are obtained in Germany, England, France, Belgium, Austria, and Russia. Some of the Herman and Belgian clay is exported to the United States. The following analyses give the composition of some American and European fire-clays: 1 2 3 4 5 52.58 Rim 46.88 36.42 1.74 .44 .20 ■ 1. 10 14. 1" 49.75 35.83 .77 33.15 .20 31.84 .67 .27 Trace i .,. e 14.23 1.92 14 . ■ i .08 [3.68 .11 .44 13.70 1.10 1 in 7 la l no Flint claj ■ Mni- t Worulbriilpe, i Flint .-i.i v . Hunker Station, Pa. 2. Point . i il lolden, I oloi ado New Jersey. 6. Stourbridge, England. Fire-clays are used in the manufacture of rirc- bricks, gas retorts, glass-pots, assayers' furni s, crucibles, and oilier objects which in their use are subjected to a high degree of heal. Vmong the varieties recognized are: Flint olay, a hard form, resembling Mini in appearance and lacking plasticity, found ill the same bed wilh plastic clay; ganister, a refractory clay having
